1. Field of the Invention
The present invention relates to a semiconductor device having a fuse element in which melting or blowout caused by electrostatic noise is suppressed.
2. Description of Related Art
In a semiconductor device including an electrical circuit formed on a semiconductor substrate, a technique in which a fuse element is incorporated in a portion of the circuit so as to achieve fine adjustment of the circuit function after manufacturing the device has been used. For example, as shown in FIG. 4, in a structure in which a power source Vcc is connected via a fuse element 12 to an internal circuit 10, a control line 16 is extended toward an electrode 14 provided outside a semiconductor device from one end a of the fuse element 12 to which the power source Vcc is not connected.
If it is not necessary to apply the power source Vcc to the internal circuit 10, the electrode 14 is set to a negative voltage which allows an electric current of an intensity causing blowout of the fuse element 12 to flow in the fuse element 12, so that the fuse element 12 can melt or blow out to break the connection between the internal circuit 10 and the power source Vcc.
In the circuit structure shown in FIG. 4, however, there is a disadvantage that the fuse element 12 may blow out or melt regardless of whether or not it is necessary, when electrostatic noise of the negative voltage is applied for a certain reason to the electrode 14 provided outside the semiconductor device. Further, as the control line 16 is directly connected with the fuse element 12, it is not possible to provide an electrostatic breakdown protection circuit for electrostatic noise on the control line 16.